空气中合成固溶体荧光粉Ba_2(Zn,Mg)Si_2O_7∶Eu~(2+),Eu~(3+),Ce~(3+)及其发光特性

采用高温固相法在空气中合成了Ba1.97-yZn1-xMgxSi2O7∶0.03Eu,y Ce3+系列荧光粉。分别采用X-射线衍射和荧光光谱对所合成荧光粉的物相和发光性质进行了表征。在紫外光330~360 nm激发下,固溶体荧光粉Ba1.97-yZn1-xMgxSi2O7∶0.03Eu的发射光谱在350~725 nm范围内呈现多谱峰发射,360和500 nm处有强的宽带发射属于Eu2+离子的4f 65d1-4f 7跃迁,590~725 nm红光区窄带谱源于Eu3+的5D0-7FJ(J=1,2,3,4)跃迁,这表明,在空气气氛中,部分Eu3+在Ba1.97-yZn1-xMgxSi2O7基质中被还原成了Eu2+;当x=0.1时,荧光粉Ba1.97Zn0.9Mg0.1Si2O7∶0.03Eu的绿色发光最强,表明Eu3+被还原成Eu2+离子的程度最大。当共掺入Ce3+离子后,形成Ba1.97-yZn0.9Mg0.1Si2O7∶0.03Eu,y Ce3+荧光粉体系,其发光随着Ce3+离子浓度的增大由蓝绿区经白光区到达橙红区;发现名义组成为Ba1.96Zn0.9Mg0.1Si2O7∶0.03Eu,0.01Ce3+的荧光粉的色坐标为(0.323,0.311),接近理想白光,是一种有潜在应用价值的白光荧光粉。讨论了稀土离子在Ba2Zn0.9Mg0.1Si2O7基质中的能量传递与发光机理。

Solid-Solution Phosphor Ba2(Zn,Mg)Si2O7:Eu2+,Eu3+,Ce3+ Prepared in Air and Its Luminescent Properties

Ba_1.97Zn_1-xMg_xSi₂O₇:0.03Eu and Ba_1.97-yZn_0.9Mg_0.1Si₂O₇:0.03Eu,yCe³⁺ phosphors were synthesized in air condition by a high temperature solid-state reaction. Crystallization and optical properties were investigated by using powder X-ray diffraction and fluorescence spectrophotometer, respectively. Under the excitation of ultraviolet (330~360 nm), the emission spectra of these solid-solution phosphors exhibit multi-emission bands peaked at about 360 nm(blue-purple color), 500 nm (green color) and 590~725 nm (red color), the two formers are corresponding to the 4f⁶5d¹-4f⁷ transition of Eu²⁺, the latter is originated from the ⁵D₀-⁷F_J (J=1,2,3,4) transitions of Eu³⁺. The investigated results indicate that part of Eu³⁺ can be self-reduced to Eu²⁺ in the matrix and will reach the maximum when x=0.1 mol. When co-doping Ce³⁺ ions, the luminescent colors of the phosphors Ba_1.97-yZn_0.9 Mg_0.1Si₂O₇:0.03Eu,yCe³⁺ can be tunable from green to white to orange area. It had been found that the nominal composition Ba_1.96Zn_0.9Mg_0.1Si₂O₇:0.03Eu,0.01Ce³⁺ phosphor provides a white emission (0.323, 0.311) that is very close to the standard white (x=0.33, y=0.33), which shows that it is a potential white phosphor for LED-based UV-chip. The energy transfer processes among rare earths and the luminescent mechanism were discussed.